Hall effect sensors are the industry choice for medium sensitivity magnetic sensors due to low cost, small area, and easy integrability. However, all semiconductor Hall effect sensors suffer from offset resulting from fabrication process nonidealities such as mismatch, doping variations, and undesired piezoelectric effects. A technique referred to as “spinning current” partially reduces the offset at the expense of severe bandwidth degradation. Even the residual offset is large enough to limit accuracy in many applications. Moreover, the residual offset drifts depending on factors such as temperature, packaging, stress, variation, and aging.
The so called “Hall Effect” occurs when a magnetic field is oriented perpendicular to an electric current. Typical Hall sensors usually include a strip or plate of an electrically conductive material with an electric current flowing through the plate. When the plate is positioned in a magnetic field such that a component of the field is perpendicular to the plate, a Hall voltage is generated within the plate in a direction that is perpendicular to both the direction of the magnetic field and the direction of the current flow.
Semiconductor Hall effect sensors typically include a sensing element produced from silicon. The magnetic sensitivity of these devices is directly related to, and limited by, the electron mobility, mu, of the material used to construct the sensing element. Silicon typically has an electron mobility of approximately 1500 cm 2/(Vs).